1
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Rallapalli H, McCall EC, Koretsky AP. Genetic control of MRI contrast using the manganese transporter Zip14. Magn Reson Med 2024; 92:820-835. [PMID: 38573932 PMCID: PMC11142883 DOI: 10.1002/mrm.29993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/15/2023] [Accepted: 12/12/2023] [Indexed: 04/06/2024]
Abstract
PURPOSE Gene-expression reporter systems, such as green fluorescent protein, have been instrumental to understanding biological processes in living organisms at organ system, tissue, cell, and molecular scales. More than 30 years of work on developing MRI-visible gene-expression reporter systems has resulted in a variety of clever application-specific methods. However, these techniques have not yet been widely adopted, so a general-purpose expression reporter is still required. Here, we demonstrate that the manganese ion transporter Zip14 is an in vivo MRI-visible, flexible, and robust gene-expression reporter to meet this need. METHODS Plasmid constructs consisting of a cell type-specific promoter, gene coding for human Zip14, and a histology-visible tag were packaged into adeno-associated viruses. These viruses were intracranially injected into the mouse brain. Serial in vivo MRI was performed using a vendor-supplied 3D-MPRAGE sequence. No additional contrast agents were administered. Animals were sacrificed after the last imaging timepoint for immunohistological validation. RESULTS Neuron-specific overexpression of Zip14 produced substantial and long-lasting changes in MRI contrast. Using appropriate viruses enabled both anterograde and retrograde neural tracing. Expression of Zip14 in astrocytes also enabled MRI of glia populations in the living mammalian brain. CONCLUSIONS The flexibility of this system as an MRI-visible gene-expression reporter will enable many applications of serial, high-resolution imaging of gene expression for basic science and therapy development.
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Affiliation(s)
- Harikrishna Rallapalli
- Section on Plasticity and Imaging of the Nervous System, NINDS/NIH, Bethesda, Maryland, USA
| | - Eleanor C McCall
- Section on Plasticity and Imaging of the Nervous System, NINDS/NIH, Bethesda, Maryland, USA
| | - Alan P Koretsky
- Section on Plasticity and Imaging of the Nervous System, NINDS/NIH, Bethesda, Maryland, USA
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2
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Prajapati M, Zhang JZ, Chong GS, Chiu L, Mercadante CJ, Kowalski HL, Antipova O, Lai B, Ralle M, Jackson BP, Punshon T, Guo S, Aghajan M, Bartnikas TB. Manganese transporter SLC30A10 and iron transporters SLC40A1 and SLC11A2 impact dietary manganese absorption. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.17.603814. [PMID: 39071439 PMCID: PMC11275741 DOI: 10.1101/2024.07.17.603814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
SLC30A10 deficiency is a disease of severe manganese excess attributed to loss of SLC30A10-dependent manganese excretion via the gastrointestinal tract. Patients develop dystonia, cirrhosis, and polycythemia. They are treated with chelators but also respond to oral iron, suggesting that iron can outcompete manganese for absorption in this disease. Here we explore the latter observation. Intriguingly, manganese absorption is increased in Slc30a10-deficient mice despite manganese excess. Studies of multiple mouse models indicate that increased dietary manganese absorption reflects two processes: loss of manganese export from enterocytes into the gastrointestinal tract lumen by SLC30A10, and increased absorption of dietary manganese by iron transporters SLC11A2 (DMT1) and SLC40A1 (ferroportin). Our work demonstrates that aberrant absorption contributes prominently to SLC30A10 deficiency and expands our understanding of biological interactions between iron and manganese. Based on these results, we propose a reconsideration of the role of iron transporters in manganese homeostasis is warranted.
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Affiliation(s)
- Milankumar Prajapati
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
| | - Jared Z. Zhang
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
| | - Grace S. Chong
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
| | - Lauren Chiu
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
| | - Courtney J. Mercadante
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
| | - Heather L. Kowalski
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
| | - Olga Antipova
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Barry Lai
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Martina Ralle
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Brian P. Jackson
- Biomedical National Elemental Imaging Resource, Dartmouth College, Hanover, NH, 03755, USA
| | - Tracy Punshon
- Biomedical National Elemental Imaging Resource, Dartmouth College, Hanover, NH, 03755, USA
| | - Shuling Guo
- Ionis Pharmaceuticals, Inc., Carlsbad, CA, 92010, USA
| | | | - Thomas B. Bartnikas
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA
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3
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Fenaroli F, Valerio A, Ingrassia R. Ischemic Neuroprotection by Insulin with Down-Regulation of Divalent Metal Transporter 1 (DMT1) Expression and Ferrous Iron-Dependent Cell Death. Biomolecules 2024; 14:856. [PMID: 39062570 PMCID: PMC11274861 DOI: 10.3390/biom14070856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 07/02/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024] Open
Abstract
Background: The regulation of divalent metal transporter-1 (DMT1) by insulin has been previously described in Langerhans cells and significant neuroprotection was found by insulin and insulin-like growth factor 1 treatment during experimental cerebral ischemia in acute ischemic stroke patients and in a rat 6-OHDA model of Parkinson's disease, where DMT1 involvement is described. According to the regulation of DMT1, previously described as a target gene of NF-kB in the early phase of post-ischemic neurodegeneration, both in vitro and in vivo, and because insulin controls the NFkB signaling with protection from ischemic cell death in rat cardiomyocytes, we evaluated the role of insulin in relation to DMT1 expression and function during ischemic neurodegeneration. Methods: Insulin neuroprotection is evaluated in differentiated human neuroblastoma cells, SK-N-SH, and in primary mouse cortical neurons exposed to oxygen glucose deprivation (OGD) for 8 h or 3 h, respectively, with or without 300 nM insulin. The insulin neuroprotection during OGD was evaluated in both cellular models in terms of cell death, and in SK-N-SH for DMT1 protein expression and acute ferrous iron treatment, performed in acidic conditions, known to promote the maximum DMT1 uptake as a proton co-transporter; and the transactivation of 1B/DMT1 mouse promoter, already known to be responsive to NF-kB, was analyzed in primary mouse cortical neurons. Results: Insulin neuroprotection during OGD was concomitant to the down-regulation of both DMT1 protein expression and 1B/DMT1 mouse promoter transactivation. We also showed the insulin-dependent protection from cell death after acute ferrous iron treatment. In conclusion, although preliminary, this evaluation highlights the peculiar role of DMT1 as a possible pharmacological target, involved in neuroprotection by insulin during in vitro neuronal ischemia and acute ferrous iron uptake.
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Affiliation(s)
- Francesca Fenaroli
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, 25123 Brescia, Italy (A.V.)
| | - Alessandra Valerio
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, 25123 Brescia, Italy (A.V.)
| | - Rosaria Ingrassia
- Section of Biotechnologies, Department of Molecular and Translational Medicine, University of Brescia, 25123 Brescia, Italy
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4
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Hounjet J, Groot AJ, Piepers JP, Kranenburg O, Zwijnenburg DA, Rapino FA, Koster JB, Kampen KR, Vooijs MA. Iron-responsive element of Divalent metal transporter 1 (Dmt1) controls Notch-mediated cell fates. FEBS J 2023; 290:5811-5834. [PMID: 37646174 DOI: 10.1111/febs.16946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 07/12/2023] [Accepted: 08/29/2023] [Indexed: 09/01/2023]
Abstract
Notch receptor activation is regulated by the intramembrane protease γ-secretase, which cleaves and liberates the Notch intracellular domain (Nicd) that regulates gene transcription. While γ-secretase cleavage is necessary, we demonstrate it is insufficient for Notch activation and requires vesicular trafficking. Here, we report Divalent metal transporter 1 (Dmt1, Slc11A2) as a novel and essential regulator of Notch signalling. Dmt1-deficient cells are defective in Notch signalling and have perturbed endolysosomal trafficking and function. Dmt1 encodes for two isoforms, with and without an iron response element (ire). We show that isoform-specific silencing of Dmt1-ire and Dmt1+ire has opposite consequences on Notch-dependent cell fates in cell lines and intestinal organoids. Loss of Dmt1-ire suppresses Notch activation and promotes differentiation, whereas loss of Dmt1+ire causes Notch activation and maintains stem-progenitor cell fates. Dmt1 isoform expression correlates with Notch and Wnt signalling in Apc-deficient intestinal organoids and human colorectal cancers. Consistently, Dmt1-ire silencing induces Notch-dependent differentiation in colorectal cancer cells. These data identify Dmt1 isoforms as binary switches controlling Notch cell fate decisions in normal and tumour cells.
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Affiliation(s)
- Judith Hounjet
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Arjan J Groot
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Jolanda P Piepers
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Onno Kranenburg
- Lab Translational Oncology, Division Imaging and Cancer, University Medical Center Utrecht, The Netherlands
| | - Danny A Zwijnenburg
- Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, The Netherlands
| | - Francesca A Rapino
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
- Department of Pharmacy, Giga Stem Cells, University of Liege, Belgium
| | - Jan B Koster
- Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, The Netherlands
| | - Kim R Kampen
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Marc A Vooijs
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
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5
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Baj J, Flieger W, Barbachowska A, Kowalska B, Flieger M, Forma A, Teresiński G, Portincasa P, Buszewicz G, Radzikowska-Büchner E, Flieger J. Consequences of Disturbing Manganese Homeostasis. Int J Mol Sci 2023; 24:14959. [PMID: 37834407 PMCID: PMC10573482 DOI: 10.3390/ijms241914959] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/01/2023] [Accepted: 10/04/2023] [Indexed: 10/15/2023] Open
Abstract
Manganese (Mn) is an essential trace element with unique functions in the body; it acts as a cofactor for many enzymes involved in energy metabolism, the endogenous antioxidant enzyme systems, neurotransmitter production, and the regulation of reproductive hormones. However, overexposure to Mn is toxic, particularly to the central nervous system (CNS) due to it causing the progressive destruction of nerve cells. Exposure to manganese is widespread and occurs by inhalation, ingestion, or dermal contact. Associations have been observed between Mn accumulation and neurodegenerative diseases such as manganism, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. People with genetic diseases associated with a mutation in the gene associated with impaired Mn excretion, kidney disease, iron deficiency, or a vegetarian diet are at particular risk of excessive exposure to Mn. This review has collected data on the current knowledge of the source of Mn exposure, the experimental data supporting the dispersive accumulation of Mn in the brain, the controversies surrounding the reference values of biomarkers related to Mn status in different matrices, and the competitiveness of Mn with other metals, such as iron (Fe), magnesium (Mg), zinc (Zn), copper (Cu), lead (Pb), calcium (Ca). The disturbed homeostasis of Mn in the body has been connected with susceptibility to neurodegenerative diseases, fertility, and infectious diseases. The current evidence on the involvement of Mn in metabolic diseases, such as type 2 diabetes mellitus/insulin resistance, osteoporosis, obesity, atherosclerosis, and non-alcoholic fatty liver disease, was collected and discussed.
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Affiliation(s)
- Jacek Baj
- Chair and Department of Anatomy, Medical University of Lublin, 20-090 Lublin, Poland; (W.F.); (A.F.)
| | - Wojciech Flieger
- Chair and Department of Anatomy, Medical University of Lublin, 20-090 Lublin, Poland; (W.F.); (A.F.)
| | - Aleksandra Barbachowska
- Department of Plastic, Reconstructive and Burn Surgery, Medical University of Lublin, 21-010 Łęczna, Poland;
| | - Beata Kowalska
- Department of Water Supply and Wastewater Disposal, Lublin University of Technology, 20-618 Lublin, Poland;
| | - Michał Flieger
- Chair and Department of Forensic Medicine, Medical University of Lublin, 20-090 Lublin, Poland; (M.F.); (G.T.); (G.B.)
| | - Alicja Forma
- Chair and Department of Anatomy, Medical University of Lublin, 20-090 Lublin, Poland; (W.F.); (A.F.)
| | - Grzegorz Teresiński
- Chair and Department of Forensic Medicine, Medical University of Lublin, 20-090 Lublin, Poland; (M.F.); (G.T.); (G.B.)
| | - Piero Portincasa
- Clinica Medica A. Murri, Department of Biomedical Sciences & Human Oncology, Medical School, University of Bari, 70124 Bari, Italy;
| | - Grzegorz Buszewicz
- Chair and Department of Forensic Medicine, Medical University of Lublin, 20-090 Lublin, Poland; (M.F.); (G.T.); (G.B.)
| | | | - Jolanta Flieger
- Department of Analytical Chemistry, Medical University of Lublin, 20-093 Lublin, Poland
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6
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The Potential Roles of Blood-Brain Barrier and Blood-Cerebrospinal Fluid Barrier in Maintaining Brain Manganese Homeostasis. Nutrients 2021; 13:nu13061833. [PMID: 34072120 PMCID: PMC8227615 DOI: 10.3390/nu13061833] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 02/07/2023] Open
Abstract
Manganese (Mn) is a trace nutrient necessary for life but becomes neurotoxic at high concentrations in the brain. The brain is a “privileged” organ that is separated from systemic blood circulation mainly by two barriers. Endothelial cells within the brain form tight junctions and act as the blood–brain barrier (BBB), which physically separates circulating blood from the brain parenchyma. Between the blood and the cerebrospinal fluid (CSF) is the choroid plexus (CP), which is a tissue that acts as the blood–CSF barrier (BCB). Pharmaceuticals, proteins, and metals in the systemic circulation are unable to reach the brain and spinal cord unless transported through either of the two brain barriers. The BBB and the BCB consist of tightly connected cells that fulfill the critical role of neuroprotection and control the exchange of materials between the brain environment and blood circulation. Many recent publications provide insights into Mn transport in vivo or in cell models. In this review, we will focus on the current research regarding Mn metabolism in the brain and discuss the potential roles of the BBB and BCB in maintaining brain Mn homeostasis.
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7
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Nash B, Irollo E, Brandimarti R, Meucci O. Opioid Modulation of Neuronal Iron and Potential Contributions to NeuroHIV. Methods Mol Biol 2021; 2201:139-162. [PMID: 32975796 DOI: 10.1007/978-1-0716-0884-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Opioid use has substantially increased over recent years and remains a major driver of new HIV infections worldwide. Clinical studies indicate that opioids may exacerbate the symptoms of HIV-associated neurocognitive disorders (HAND), but the mechanisms underlying opioid-induced cognitive decline remain obscure. We recently reported that the μ-opioid agonist morphine increased neuronal iron levels and levels of ferritin proteins that store iron, suggesting that opioids modulate neuronal iron homeostasis. Additionally, increased iron and ferritin heavy chain protein were necessary for morphine's ability to reduce the density of thin and mushroom dendritic spines in cortical neurons, which are considered critical mediators of learning and memory, respectively. As altered iron homeostasis has been reported in HAND and related neurocognitive disorders like Alzheimer's, Parkinson's, and Huntington's disease, understanding how opioids regulate neuronal iron metabolism may help identify novel drug targets in HAND with potential relevance to these other neurocognitive disorders. Here, we review the known mechanisms of opioid-mediated regulation of neuronal iron and corresponding cellular responses and discuss the implications of these findings for patients with HAND. Furthermore, we discuss a new molecular approach that can be used to understand if opioid modulation of iron affects the expression and processing of amyloid precursor protein and the contributions of this pathway to HAND.
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Affiliation(s)
- Bradley Nash
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Elena Irollo
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Renato Brandimarti
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, PA, USA
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Olimpia Meucci
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, PA, USA.
- Department of Microbiology & Immunology, Drexel University College of Medicine, Philadelphia, PA, USA.
- Center for Neuroimmunology and CNS Therapeutics, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA.
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8
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Thévenod F, Lee WK, Garrick MD. Iron and Cadmium Entry Into Renal Mitochondria: Physiological and Toxicological Implications. Front Cell Dev Biol 2020; 8:848. [PMID: 32984336 PMCID: PMC7492674 DOI: 10.3389/fcell.2020.00848] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/07/2020] [Indexed: 12/15/2022] Open
Abstract
Regulation of body fluid homeostasis is a major renal function, occurring largely through epithelial solute transport in various nephron segments driven by Na+/K+-ATPase activity. Energy demands are greatest in the proximal tubule and thick ascending limb where mitochondrial ATP production occurs through oxidative phosphorylation. Mitochondria contain 20-80% of the cell's iron, copper, and manganese that are imported for their redox properties, primarily for electron transport. Redox reactions, however, also lead to reactive, toxic compounds, hence careful control of redox-active metal import into mitochondria is necessary. Current dogma claims the outer mitochondrial membrane (OMM) is freely permeable to metal ions, while the inner mitochondrial membrane (IMM) is selectively permeable. Yet we recently showed iron and manganese import at the OMM involves divalent metal transporter 1 (DMT1), an H+-coupled metal ion transporter. Thus, iron import is not only regulated by IMM mitoferrins, but also depends on the OMM to intermembrane space H+ gradient. We discuss how these mitochondrial transport processes contribute to renal injury in systemic (e.g., hemochromatosis) and local (e.g., hemoglobinuria) iron overload. Furthermore, the environmental toxicant cadmium selectively damages kidney mitochondria by "ionic mimicry" utilizing iron and calcium transporters, such as OMM DMT1 or IMM calcium uniporter, and by disrupting the electron transport chain. Consequently, unraveling mitochondrial metal ion transport may help develop new strategies to prevent kidney injury induced by metals.
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Affiliation(s)
- Frank Thévenod
- Faculty of Health, Centre for Biomedical Education and Research, Institute of Physiology, Pathophysiology and Toxicology, Witten/Herdecke University, Witten, Germany
| | - Wing-Kee Lee
- Faculty of Health, Centre for Biomedical Education and Research, Institute of Physiology, Pathophysiology and Toxicology, Witten/Herdecke University, Witten, Germany
| | - Michael D Garrick
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
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9
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Iron-responsive-like elements and neurodegenerative ferroptosis. ACTA ACUST UNITED AC 2020; 27:395-413. [PMID: 32817306 PMCID: PMC7433652 DOI: 10.1101/lm.052282.120] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 12/26/2022]
Abstract
A set of common-acting iron-responsive 5′untranslated region (5′UTR) motifs can fold into RNA stem loops that appear significant to the biology of cognitive declines of Parkinson's disease dementia (PDD), Lewy body dementia (LDD), and Alzheimer's disease (AD). Neurodegenerative diseases exhibit perturbations of iron homeostasis in defined brain subregions over characteristic time intervals of progression. While misfolding of Aβ from the amyloid-precursor-protein (APP), alpha-synuclein, prion protein (PrP) each cause neuropathic protein inclusions in the brain subregions, iron-responsive-like element (IRE-like) RNA stem–loops reside in their transcripts. APP and αsyn have a role in iron transport while gene duplications elevate the expression of their products to cause rare familial cases of AD and PDD. Of note, IRE-like sequences are responsive to excesses of brain iron in a potential feedback loop to accelerate neuronal ferroptosis and cognitive declines as well as amyloidosis. This pathogenic feedback is consistent with the translational control of the iron storage protein ferritin. We discuss how the IRE-like RNA motifs in the 5′UTRs of APP, alpha-synuclein and PrP mRNAs represent uniquely folded drug targets for therapies to prevent perturbed iron homeostasis that accelerates AD, PD, PD dementia (PDD) and Lewy body dementia, thus preventing cognitive deficits. Inhibition of alpha-synuclein translation is an option to block manganese toxicity associated with early childhood cognitive problems and manganism while Pb toxicity is epigenetically associated with attention deficit and later-stage AD. Pathologies of heavy metal toxicity centered on an embargo of iron export may be treated with activators of APP and ferritin and inhibitors of alpha-synuclein translation.
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10
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Garrick MD, Garrick LM, Zhao L, Collins JF, Soukup J, Ghio AJ. A direct comparison of divalent metal-ion transporter (DMT1) and hinokitiol, a potential small molecule replacement. Biometals 2019; 32:745-755. [PMID: 31368012 PMCID: PMC6768898 DOI: 10.1007/s10534-019-00207-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/22/2019] [Indexed: 01/01/2023]
Abstract
Hinokitiol, a natural lipophilic chelator, appears capable of replacing several iron transporters after they have been genetically ablated. Divalent metal-ion transporter (DMT1) is the major iron importer in enterocytes and erythroblasts. We have compared DMT1 and hinokitiol in multiple fashions to learn if the smaller molecule is a suitable substitute using two HEK293 cell lines engineered to overexpress different isoforms of DMT1. Both the macromolecule and the lipophilic chelator enable import of ferrous ions into HEK293 cells. Hinokitiol also mediates ferric ion import but DMT1 cannot do so. While DMT1 can also import Mn2+ ions, hinokitiol lacks this ability. The Michaelis–Menten analysis for kinetics of macromolecular catalysis is also suitable for hinokitiol-supported iron import. To compare hinokitiol to DMT1 relative to other metal ions that DMT1 can transport, we employed an organic extraction procedure with which we initially matched the results obtained for Fe2+, Fe3+ and Mn2+, and then showed that multiple other cations were unlikely to enter via hinokitiol. The small chelator thus shares some functional properties with DMT1, but distinct difference were also noted.
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Affiliation(s)
- Michael D Garrick
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA. .,Department of Pediatrics, University at Buffalo, Buffalo, NY, USA.
| | - Laura M Garrick
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA
| | - Lin Zhao
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Joleen Soukup
- National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
| | - Andrew J Ghio
- National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
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11
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Ingrassia R, Garavaglia B, Memo M. DMT1 Expression and Iron Levels at the Crossroads Between Aging and Neurodegeneration. Front Neurosci 2019; 13:575. [PMID: 31231185 PMCID: PMC6560079 DOI: 10.3389/fnins.2019.00575] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 05/20/2019] [Indexed: 12/15/2022] Open
Abstract
Iron homeostasis is an essential prerequisite for metabolic and neurological functions throughout the healthy human life, with a dynamic interplay between intracellular and systemic iron metabolism. The development of different neurodegenerative diseases is associated with alterations of the intracellular transport of iron and heavy metals, principally mediated by Divalent Metal Transporter 1 (DMT1), responsible for Non-Transferrin Bound Iron transport (NTBI). In addition, DMT1 regulation and its compartmentalization in specific brain regions play important roles during aging. This review highlights the contribution of DMT1 to the physiological exchange and distribution of body iron and heavy metals during aging and neurodegenerative diseases. DMT1 also mediates the crosstalk between central nervous system and peripheral tissues, by systemic diffusion through the Blood Brain Barrier (BBB), with the involvement of peripheral iron homeostasis in association with inflammation. In conclusion, a survey about the role of DMT1 and iron will illustrate the complex panel of interrelationship with aging, neurodegeneration and neuroinflammation.
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Affiliation(s)
- Rosaria Ingrassia
- Section of Biotechnologies, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Barbara Garavaglia
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Maurizio Memo
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
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12
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Wang X, Zhang M, Flores SRL, Woloshun RR, Yang C, Yin L, Xiang P, Xu X, Garrick MD, Vidyasagar S, Merlin D, Collins JF. Oral Gavage of Ginger Nanoparticle-Derived Lipid Vectors Carrying Dmt1 siRNA Blunts Iron Loading in Murine Hereditary Hemochromatosis. Mol Ther 2019; 27:493-506. [PMID: 30713087 PMCID: PMC6401192 DOI: 10.1016/j.ymthe.2019.01.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/21/2018] [Accepted: 01/08/2019] [Indexed: 12/19/2022] Open
Abstract
Nanoparticles (NPs) have been utilized to deliver drugs to the intestinal epithelium in vivo. Moreover, NPs derived from edible plants are less toxic than synthetic NPs. Here, we utilized ginger NP-derived lipid vectors (GDLVs) in a proof-of-concept investigation to test the hypothesis that inhibiting expression of divalent metal-ion transporter 1 (Dmt1) would attenuate iron loading in a mouse model of hereditary hemochromatosis (HH). Initial experiments using duodenal epithelial organ cultures from intestine-specific Dmt1 knockout (KO) (Dmt1int/int) mice in the Ussing chamber established that Dmt1 is the only active iron importer during iron-deficiency anemia. Further, when Dmt1int/int mice were crossed with mice lacking the iron-regulatory hormone, hepcidin (Hepc-/-), iron loading was abolished. Hence, intestinal Dmt1 is required for the excessive iron absorption that typifies HH. Additional experiments established a protocol to produce GDLVs carrying functional Dmt1 small interfering RNAs (siRNAs) and to target these gene delivery vehicles to the duodenal epithelium in vivo (by incorporating folic acid [FA]). When FA-GDLVs carrying Dmt1 siRNA were administered to weanling Hepc-/- mice for 16 days, intestinal Dmt1 mRNA expression was attenuated and tissue iron accumulation was blunted. Oral delivery of functional siRNAs by FA-GDLVs is a suitable therapeutic approach to mitigate iron loading in murine HH.
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Affiliation(s)
- Xiaoyu Wang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Mingzhen Zhang
- Institute of Medical Engineering, School of Basic Medical Science, Health Science Center, Xi'an Jiaotong University, Xi'an, China; Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, USA
| | - Shireen R L Flores
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Regina R Woloshun
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Chunhua Yang
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, USA
| | - Liangjie Yin
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
| | - Ping Xiang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA; State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China
| | - Xiaodong Xu
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
| | - Michael D Garrick
- Department of Biochemistry, State University of New York (SUNY), Buffalo, NY, USA
| | | | - Didier Merlin
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, USA; Atlanta Veterans Affairs Medical Center, Decatur, GA, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA.
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13
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Pokrowiecki R, Pałka K, Mielczarek A. Nanomaterials in dentistry: a cornerstone or a black box? Nanomedicine (Lond) 2018; 13:639-667. [DOI: 10.2217/nnm-2017-0329] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Aim: The studies on tooth structure provided basis for nanotechnology-based dental treatment approaches known as nanodentistry which aims at detection and treatment of oral pathologies, such as dental caries and periodontal diseases, insufficiently being treated by conventional materials or drugs. This review aims at defining the role of nanodentistry in the medical area, its potential and hazards. Materials & methods: To validate these issues, current literature on nanomaterials for dental applications was critically reviewed. Results: Nanomaterials for teeth restoration, bone regeneration and oral implantology exhibit better mechanical properties and provide more efficient esthetic outcome. However, still little is known about influence of long-term function of such biomaterials in the living organism. Conclusion: As application of nanomaterials in industry and medical-related sciences is still expanding, more information is needed on how such nano-dental materials may interfere with oral cavity, GI tract and general health.
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Affiliation(s)
- Rafał Pokrowiecki
- Department of Head & Neck Surgery – Maxillofacial Surgery, Otolaryngology & Ophthalmology, Prof Stanislaw Popowski Voivoid Children Hospital, Żołnierska 18 A10-561 Olsztyn, Poland
| | - Krzysztof Pałka
- Faculty of Mechanical Engineering, Lublin University of Technology, Lublin, Poland
| | - Agnieszka Mielczarek
- Department of Conservative Dentistry, Medical University of Warsaw, Warsaw, Poland
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14
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Maynar M, Llerena F, Bartolomé I, Alves J, Robles MC, Grijota FJ, Muñoz D. Seric concentrations of copper, chromium, manganesum, nickel and selenium in aerobic, anaerobic and mixed professional sportsmen. J Int Soc Sports Nutr 2018; 15:8. [PMID: 29449792 PMCID: PMC5812230 DOI: 10.1186/s12970-018-0212-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/09/2018] [Indexed: 12/03/2022] Open
Abstract
Background The aim of the present study was to determine changes in serum concentrations of trace elements Cooper (Cu), Chromiun (Cr), Manganesum (Mn), Nickel (Ni) and Selenium (Se) in high-level sportsmen. Methods Eighty professional athletes of different metabolic modalities, were recruited before the start of their training period. Thirty one sedentary participants of the same geographic area constituted the control group. Cu, Cr, Mn, Ni and Se analysis was performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results Higher concentrations of Cr (p < 0.001), Mn (p < 0.085), and Ni (p < 0.001) were found in sportsmen in comparison to controls, inversely, Se values were lower (p < 0.001) among sportsmen. When sportsmen were classified by metabolic modalities, it was found that aerobic-anaerobic group had higher (p < 0.01) Cu concentrations than controls and the other sportsmen. The highest Cr values were found in aerobic participants. For Mn, the major levels were found in aerobic and aerobic-anaerobic groups as well (p < 0.001). The lowest Se levels were found among anaerobic sportsmen (p < 0.001). Conclusion This research showed that daily, continuum physical training induced alterations in serum essential minerals concentrations, as well as that these changes can be dependent of the exercise modality practiced.
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Affiliation(s)
- Marcos Maynar
- 1Department of Physiology, School of Sport Sciences, University of Extremadura, University Avenue, 10003 Cáceres, Spain
| | - Francisco Llerena
- 2Department of Medical-Surgical Therapeutics, School of Medicine, University of Extremadura, Elvas Avenue, 06071 Badajoz, Spain
| | - Ignacio Bartolomé
- 1Department of Physiology, School of Sport Sciences, University of Extremadura, University Avenue, 10003 Cáceres, Spain
| | - Javier Alves
- 3Department of Sport Sciences, School of Sport Sciences, Pontifical University of Salamanca, Henry Collet Street, 53, 37007 Salamanca, Spain
| | - María-Concepción Robles
- 4Department of Physical Education and Sport, School of Sport Sciences, University of Extremadura, University Avenue, 10003 Cáceres, Spain
| | - Francisco-Javier Grijota
- 3Department of Sport Sciences, School of Sport Sciences, Pontifical University of Salamanca, Henry Collet Street, 53, 37007 Salamanca, Spain
| | - Diego Muñoz
- 4Department of Physical Education and Sport, School of Sport Sciences, University of Extremadura, University Avenue, 10003 Cáceres, Spain
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15
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A role for divalent metal transporter (DMT1) in mitochondrial uptake of iron and manganese. Sci Rep 2018; 8:211. [PMID: 29317744 PMCID: PMC5760699 DOI: 10.1038/s41598-017-18584-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 12/13/2017] [Indexed: 01/01/2023] Open
Abstract
Much of iron and manganese metabolism occurs in mitochondria. Uptake of redox-active iron must be tightly controlled, but little is known about how metal ions enter mitochondria. Recently, we established that the divalent metal transporter 1 (DMT1) is present in the outer mitochondrial membrane (OMM). Therefore we asked if it mediates Fe2+ and Mn2+ influx. Mitochondria were isolated from HEK293 cells permanently transfected with inducible rat DMT1 isoform 1 A/+IRE (HEK293-rDMT1). Fe2+-induced quenching of the dye PhenGreen™SK (PGSK) occurred in two phases, one of which reflected OMM DMT1 with stronger Fe2+ uptake after DMT1 overexpression. DMT1-specific quenching showed an apparent affinity of ~1.5 µM for Fe2+and was blocked by the DMT1 inhibitor CISMBI. Fe2+ influx reflected an imposed proton gradient, a response that was also observed in purified rat kidney cortex (rKC) mitochondria. Non-heme Fe accumulation assayed by ICPOES and stable 57Fe isotope incorporation by ICPMS were increased in HEK293-rDMT1 mitochondria. HEK293-rDMT1 mitochondria displayed higher 59Fe2+ and 54Mn2+ uptake relative to controls with 54Mn2+ uptake blocked by the DMT1 inhibitor XEN602. Such transport was defective in rKC mitochondria with the Belgrade (G185R) mutation. Thus, these results support a role for DMT1 in mitochondrial Fe2+ and Mn2+ acquisition.
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16
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Asthana A, Baksi S, Ashok A, Karmakar S, Mammadova N, Kokemuller R, Greenlee MH, Kong Q, Singh N. Prion protein facilitates retinal iron uptake and is cleaved at the β-site: Implications for retinal iron homeostasis in prion disorders. Sci Rep 2017; 7:9600. [PMID: 28851903 PMCID: PMC5575325 DOI: 10.1038/s41598-017-08821-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/17/2017] [Indexed: 12/22/2022] Open
Abstract
Prion disease-associated retinal degeneration is attributed to PrP-scrapie (PrPSc), a misfolded isoform of prion protein (PrPC) that accumulates in the neuroretina. However, a lack of temporal and spatial correlation between PrPSc and cytotoxicity suggests the contribution of host factors. We report retinal iron dyshomeostasis as one such factor. PrPC is expressed on the basolateral membrane of retinal-pigment-epithelial (RPE) cells, where it mediates uptake of iron by the neuroretina. Accordingly, the neuroretina of PrP-knock-out mice is iron-deficient. In RPE19 cells, silencing of PrPC decreases ferritin while over-expression upregulates ferritin and divalent-metal-transporter-1 (DMT-1), indicating PrPC-mediated iron uptake through DMT-1. Polarization of RPE19 cells results in upregulation of ferritin by ~10-fold and β-cleavage of PrPC, the latter likely to block further uptake of iron due to cleavage of the ferrireductase domain. A similar β-cleavage of PrPC is observed in mouse retinal lysates. Scrapie infection causes PrPSc accumulation and microglial activation, and surprisingly, upregulation of transferrin despite increased levels of ferritin. Notably, detergent-insoluble ferritin accumulates in RPE cells and correlates temporally with microglial activation, not PrPSc accumulation, suggesting that impaired uptake of iron by PrPSc combined with inflammation results in retinal iron-dyshomeostasis, a potentially toxic host response contributing to prion disease-associated pathology.
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Affiliation(s)
- Abhishek Asthana
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Shounak Baksi
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Ajay Ashok
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Shilpita Karmakar
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Najiba Mammadova
- Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, Iowa, 50010, USA
| | - Robyn Kokemuller
- Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, Iowa, 50010, USA
| | - Mary Heather Greenlee
- Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, Iowa, 50010, USA
| | - Qingzhong Kong
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Neena Singh
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA.
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17
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Roussel G, Stevens V, Cottin S, McArdle HJ. The effect of amino acid deprivation on the transfer of iron through Caco-2 cell monolayers. J Trace Elem Med Biol 2017; 40:82-90. [PMID: 28159226 DOI: 10.1016/j.jtemb.2016.12.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 12/31/2016] [Indexed: 11/25/2022]
Abstract
Iron (Fe) metabolism is modified by many nutritional factors. Amino acids (AA) play a central role in various biological processes, such as protein synthesis and energy supply. However, the influence of AA status on iron metabolism has not been investigated. Here, we test whether AA alters iron metabolism in an intestinal cell model. Both Fe uptake and transfer across the cell monolayer were significantly increased by non-essential AA deficiency (both p<0.001) while only Fe transfer was increased by essential AA deficiency (p<0.0001). Both essential and non-essential AA deficiency decreased DMT1 (±IRE) exon1A mRNA expression (respectively p=0.0007 and p=0.006) and increased expression of ferritin heavy chain. DMT1+IRE (also expressing exon1A or 1B) mRNA levels were decreased by essential AA deficiency (p=0.012). The mRNA levels of total DMT1 were also decreased by essential, but not non-essential, AA deficiency (p=0.006). Hepcidin levels were increased significantly by non-essential amino acid deprivation (p=0.047). Protein levels of ferroportin and/or ferritin heavy chain were not altered by AA deficiency, suggesting that they had no effect on Fe efflux or storage in the cell, though iron content of ferritin could be increased. Our data demonstrate, for the first time, that AA status affects iron transport and the expression of genes related to iron metabolism in Caco-2 cells, although the changes observed are not sufficient to explain the alteration in iron transport. We hypothesise that the effect on Fe transfer is mediated through an increased movement across the cell layer, rather than transfer across the cell membranes.
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Affiliation(s)
- Guenievre Roussel
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
| | - Valerie Stevens
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
| | - Sarah Cottin
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
| | - Harry J McArdle
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
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18
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Ingrassia R, Memo M, Garavaglia B. Ferrous Iron Up-regulation in Fibroblasts of Patients with Beta Propeller Protein-Associated Neurodegeneration (BPAN). Front Genet 2017; 8:18. [PMID: 28261264 PMCID: PMC5314138 DOI: 10.3389/fgene.2017.00018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/06/2017] [Indexed: 11/13/2022] Open
Abstract
Mutations in WDR45 gene, coding for a beta-propeller protein, have been found in patients affected by Neurodegeneration with Brain Iron Accumulation, NBIA5 (also known as BPAN). BPAN is a movement disorder with Non Transferrin Bound Iron (NTBI) accumulation in the basal ganglia as common hallmark between NBIA classes (Hayflick et al., 2013). WDR45 has been predicted to have a role in autophagy, while the impairment of iron metabolism in the different NBIA subclasses has not currently been clarified. We found the up-regulation of the ferrous iron transporter (-)IRE/Divalent Metal Transporter1 and down-regulation of Transferrin receptor in the fibroblasts of two BPAN affected patients with splicing mutations 235+1G>A (BPAN1) and 517_519ΔVal 173 (BPAN2). The BPAN patients showed a concomitant increase of intracellular ferrous iron after starvation. An altered pattern of iron transporters with iron overload is highlighted in BPAN human fibroblasts, supporting for a role of DMT1 in NBIA. We here present a novel element, about iron accumulation, to the existing knowledge in field of NBIA. Attention is focused to a starvation-dependent iron overload, possibly accounting for iron accumulation in the basal ganglia. Further investigation could clarify iron regulation in BPAN.
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Affiliation(s)
- Rosaria Ingrassia
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia Brescia, Italy
| | - Maurizio Memo
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia Brescia, Italy
| | - Barbara Garavaglia
- Molecular Neurogenetics Unit, Foundation IRCCS Neurological Institute Carlo Besta Milan, Italy
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19
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Meltzer HM, Alexander J, Brantsæter AL, Borch-Iohnsen B, Ellingsen DG, Thomassen Y, Holmen J, Ydersbond TA. The impact of iron status and smoking on blood divalent metal concentrations in Norwegian women in the HUNT2 Study. J Trace Elem Med Biol 2016; 38:165-173. [PMID: 27108098 DOI: 10.1016/j.jtemb.2016.04.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/09/2016] [Accepted: 04/14/2016] [Indexed: 01/20/2023]
Abstract
Low iron (Fe) stores may result in increased absorption of divalent metals, in particular cadmium (Cd). We have previously shown that in non-smoking women participating in the Norwegian HUNT2 cohort study this also included other divalent metals, e.g. manganese (Mn) and cobalt (Co). The diet is the main source of metals in non-smoking individuals, whereas in smoking individuals tobacco smoke contributes significant amounts of Cd and lead (Pb). The aim of the present study was to investigate the impact of smoking on the relationship between low iron status and divalent metals. Blood concentrations of the divalent metals Cd, Mn, Co, Pb, copper (Cu) and zinc (Zn), determined using an Element 2 sector field mass spectrometer (ICP-MS), were investigated in smoking women of fertile age (range 21-55 years) (n=267) from the HUNT2 cohort. Among these, 82 were iron-deplete (serum ferritin<12μg/L) and 28 had iron deficiency anaemia (serum ferritin<12μg/L & Hb<120g/L). 150 (56%) women smoked 10 or more cigarettes daily, 101 (38%) had smoked for more than 20 years, and 107 (40%) had smoked for 11-20 years. Results from the smoking population were compared with results from our previous study in non-smoking women (n=448) of which 132 were previous smokers, all from the same cohort. Increasing concentrations of Cd in blood were observed for previous smokers, low-to-moderate smokers and high intensity smokers in all subgroups compared to never smokers, and according to age groups, education level, BMI and serum ferritin. Smokers had higher Pb concentrations than non-smokers in all subgroups, but less pronounced than for Cd. Smoking was not associated with Mn and Co concentrations in blood. In multiple regression models, low ferritin was associated with increased blood concentrations of Cd, Pb, Mn and Co. Ferritin was strongly associated with Cd at low smoking intensity, but was not a significant factor in heavy smokers, where intensity and duration of smoking emerged as main determinants. Ferritin associations with Co and Pb varied with tertiles of blood Cd. Ferritin emerged as the main determinant of blood Co and Mn, while for blood Pb, age and smoking intensity had higher impact. Cu and Zn remained within reference values and no significant associations with ferritin were found. Strong positive associations between blood concentrations of Pb, Mn, Cd and Co were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the divalent metals studied. Mild anaemia (110<Hb<120g/L) did not seem to have any effect independent of low ferritin. The results indicate that low serum ferritin facilitates absorption of certain divalent metal ions in female smokers as well as the previously shown effect in non-smokers. Even if smoking provides Pb and Cd, the mutual associations between Cd and other divalent metals in blood persisted in medium and heavy smokers. This indicates that the interrelationship between Cd and divalent metals not only reflect effects on the absorption, but possibly also on kinetic processes such as transportation in blood and other compartments, including excretion.
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Affiliation(s)
- H M Meltzer
- Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
| | - J Alexander
- Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway
| | - A L Brantsæter
- Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway
| | - B Borch-Iohnsen
- Institute of Basic Medical Sciences, Department of Nutrition, University of Oslo, P.O. Box 1046 Blindern, N-0317 Oslo, Norway
| | - D G Ellingsen
- National Institute of Occupational Health, P.O. Box 8149 Dep., N-0033 Oslo, Norway
| | - Y Thomassen
- National Institute of Occupational Health, P.O. Box 8149 Dep., N-0033 Oslo, Norway
| | - J Holmen
- HUNT Research Center, Department of Public Health and General Practice, Norwegian University of Science and Technology, Forskningsveien 2, N-7600, Levanger, Norway
| | - T A Ydersbond
- Statistics Norway, P.O. Box 8131 Dep., N-0033 Oslo, Norway
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20
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Regulation of ATP13A2 via PHD2-HIF1α Signaling Is Critical for Cellular Iron Homeostasis: Implications for Parkinson's Disease. J Neurosci 2016; 36:1086-95. [PMID: 26818499 DOI: 10.1523/jneurosci.3117-15.2016] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED We previously reported that pharmacological inhibition of a class of enzymes known as prolyl hydroxylase domain proteins (PHDs) has neuroprotective effects in various in vitro and in vivo models of Parkinson's disease (PD). We hypothesized that this was due to inhibition of the PHD2 isoform, preventing it from hydroxylating the transcription factor hypoxia inducible factor 1 α (HIF1α), targeting it for eventual proteasomal degradation. HIF1α itself induces the transcription of various cellular stress genes, including several involved in iron metabolism. Although all three isoforms of PHD are expressed within vulnerable dopaminergic (DAergic) substantia nigra pars compacta neurons, only select downregulation of the PHD2 isoform was found to protect against in vivo neurodegenerative effects associated with the mitochondrial neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. These findings were corroborated in induced pluripotent stem cell-derived neurons, providing validation in a pertinent human cell model. PHD2 inhibition was found to result in increased expression of ATP13A2, mutation of which is responsible for a rare juvenile form of PD known as Kufor-Rakeb syndrome. Knockdown of ATP13A2 expression within human DAergic cells was found to abrogate restoration of cellular iron homeostasis and neuronal cell viability elicited by inhibition of PHD2 under conditions of mitochondrial stress, likely via effects on lysosomal iron storage. These data suggest that regulation of ATP13A2 by the PHD2-HIF1α signaling pathway affects cellular iron homeostasis and DAergic neuronal survival. This constitutes a heretofore unrecognized process associated with loss of ATP13A2 function that could have wide-ranging implications for it as a therapeutic target for PD and other related conditions. SIGNIFICANCE STATEMENT Reductions in PHD2 activity within dopaminergic neurons in vivo and in cultured human induced pluripotent stem cell-derived neurons protects against mitochondrial stress-induced neurotoxicity. Protective effects are dependent on downstream HIF-1α expression. Knockdown of ATP13A2, a gene linked to a rare juvenile form of Parkinson's disease and recently identified as a novel HIF1α target, was found to abrogate maintenance of cellular iron homeostasis and neuronal viability elicited by PHD2 inhibition in vivo and in cultured dopaminergic cells under conditions of mitochondrial stress. Mechanistically, this was due to ATP13A2's role in maintaining lysosomal iron stores. This constitutes a novel mechanism by which alterations in ATP13A2 activity may be driving PD-related neuropathology.
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Wolff NA, Garrick LM, Zhao L, Garrick MD, Thévenod F. Mitochondria represent another locale for the divalent metal transporter 1 (DMT1). Channels (Austin) 2015; 8:458-66. [PMID: 25483589 DOI: 10.4161/19336950.2014.956564] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The divalent metal transporter (DMT1) is well known for its roles in duodenal iron absorption across the apical enterocyte membrane, in iron efflux from the endosome during transferrin-dependent cellular iron acquisition, as well as in uptake of non-transferrin bound iron in many cells. Recently, using multiple approaches, we have obtained evidence that the mitochondrial outer membrane is another subcellular locale of DMT1 expression. While iron is of vital importance for mitochondrial energy metabolism, its delivery is likely to be tightly controlled due to iron's damaging redox properties. Here we provide additional support for a role of DMT1 in mitochondrial iron acquisition by immunofluorescence colocalization with mitochondrial markers in cells and isolated mitochondria, as well as flow cytometric quantification of DMT1-positive mitochondria from an inducible expression system. Physiological consequences of mitochondrial DMT1 expression are discussed also in consideration of other DMT1 substrates, such as manganese, relevant to mitochondrial antioxidant defense.
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Key Words
- AIF, apoptosis-inducing factor
- BSA, bovine serum albumin
- CHO, Chinese hamster ovary
- COXII, cytochrome C oxidase subunit II
- DMT1, divalent metal transporter 1
- HEK293, human embryonic kidney cells
- IRE, iron responsive element
- Lamp1, lysosome-associated membrane protein 1
- MRB, Mitochondrial Resuspending Buffer
- OMM, outer mitochondrial membrane
- PBS, phosphate-buffered saline
- Tf, transferrin
- Tom6/Tom20, translocase of the outer mitochondrial membrane 6 kDa subunit homolog/20 kDa subunit, respectively
- VDAC1, voltage-dependent anion-selective channel protein 1
- divalent metal transporter 1 (DMT1)
- flow cytometry
- immunofluorescence microscopy
- iron transport
- mitochondrial outer membrane
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Affiliation(s)
- Natascha A Wolff
- a Institute of Physiology; Pathophysiology & Toxicology ; University of Witten/Herdecke ; Witten , Germany
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Manganese-Induced Parkinsonism and Parkinson's Disease: Shared and Distinguishable Features. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2015; 12:7519-40. [PMID: 26154659 PMCID: PMC4515672 DOI: 10.3390/ijerph120707519] [Citation(s) in RCA: 220] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 12/12/2014] [Accepted: 01/06/2015] [Indexed: 11/30/2022]
Abstract
Manganese (Mn) is an essential trace element necessary for physiological processes that support development, growth and neuronal function. Secondary to elevated exposure or decreased excretion, Mn accumulates in the basal ganglia region of the brain and may cause a parkinsonian-like syndrome, referred to as manganism. The present review discusses the advances made in understanding the essentiality and neurotoxicity of Mn. We review occupational Mn-induced parkinsonism and the dynamic modes of Mn transport in biological systems, as well as the detection and pharmacokinetic modeling of Mn trafficking. In addition, we review some of the shared similarities, pathologic and clinical distinctions between Mn-induced parkinsonism and Parkinson’s disease. Where possible, we review the influence of Mn toxicity on dopamine, gamma aminobutyric acid (GABA), and glutamate neurotransmitter levels and function. We conclude with a survey of the preventive and treatment strategies for manganism and idiopathic Parkinson’s disease (PD).
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Skjørringe T, Burkhart A, Johnsen KB, Moos T. Divalent metal transporter 1 (DMT1) in the brain: implications for a role in iron transport at the blood-brain barrier, and neuronal and glial pathology. Front Mol Neurosci 2015; 8:19. [PMID: 26106291 PMCID: PMC4458610 DOI: 10.3389/fnmol.2015.00019] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/20/2015] [Indexed: 01/25/2023] Open
Abstract
Iron is required in a variety of essential processes in the body. In this review, we focus on iron transport in the brain and the role of the divalent metal transporter 1 (DMT1) vital for iron uptake in most cells. DMT1 locates to cellular membranes and endosomal membranes, where it is a key player in non-transferrin bound iron uptake and transferrin-bound iron uptake, respectively. Four isoforms of DMT1 exist, and their respective characteristics involve a complex cell-specific regulatory machinery all controlling iron transport across these membranes. This complexity reflects the fine balance required in iron homeostasis, as this metal is indispensable in many cell functions but highly toxic when appearing in excess. DMT1 expression in the brain is prominent in neurons. Of serious dispute is the expression of DMT1 in non-neuronal cells. Recent studies imply that DMT1 does exist in endosomes of brain capillary endothelial cells denoting the blood-brain barrier. This supports existing evidence that iron uptake at the BBB occurs by means of transferrin-receptor mediated endocytosis followed by detachment of iron from transferrin inside the acidic compartment of the endosome and DMT1-mediated pumping iron into the cytosol. The subsequent iron transport across the abluminal membrane into the brain likely occurs by ferroportin. The virtual absent expression of transferrin receptors and DMT1 in glial cells, i.e., astrocytes, microglia and oligodendrocytes, suggest that the steady state uptake of iron in glia is much lower than in neurons and/or other mechanisms for iron uptake in these cell types prevail.
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Affiliation(s)
- Tina Skjørringe
- Section of Neurobiology, Biomedicine, Institute of Medicine and Health Technology, Aalborg University Aalborg, Denmark
| | - Annette Burkhart
- Section of Neurobiology, Biomedicine, Institute of Medicine and Health Technology, Aalborg University Aalborg, Denmark
| | - Kasper Bendix Johnsen
- Section of Neurobiology, Biomedicine, Institute of Medicine and Health Technology, Aalborg University Aalborg, Denmark
| | - Torben Moos
- Section of Neurobiology, Biomedicine, Institute of Medicine and Health Technology, Aalborg University Aalborg, Denmark
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Ji C, Kosman DJ. Molecular mechanisms of non-transferrin-bound and transferring-bound iron uptake in primary hippocampal neurons. J Neurochem 2015; 133:668-83. [PMID: 25649872 DOI: 10.1111/jnc.13040] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 01/08/2015] [Accepted: 01/14/2015] [Indexed: 12/16/2022]
Abstract
The molecular mechanisms of iron trafficking in neurons have not been elucidated. In this study, we characterized the expression and localization of ferrous iron transporters Zip8, Zip14 and divalent metal transporter 1 (DMT1), and ferrireductases Steap2 and stromal cell-derived receptor 2 in primary rat hippocampal neurons. Steap2 and Zip8 partially co-localize, indicating these two proteins may function in Fe(3+) reduction prior to Fe(2+) permeation. Zip8, DMT1, and Steap2 co-localize with the transferrin receptor/transferrin complex, suggesting they may be involved in transferrin receptor/transferrin-mediated iron assimilation. In brain interstitial fluid, transferring-bound iron (TBI) and non-transferrin-bound iron (NTBI) exist as potential iron sources. Primary hippocampal neurons exhibit significant iron uptake from TBI (Transferrin-(59) Fe(3+)) and NTBI, whether presented as (59) Fe(2+) -citrate or (59) Fe(3+) -citrate; reductase-independent (59) Fe(2+) uptake was the most efficient uptake pathway of the three. Kinetic analysis of Zn(2+) inhibition of Fe(2+) uptake indicated that DMT1 plays only a minor role in the uptake of NTBI. In contrast, localization and knockdown data indicate that Zip8 makes a major contribution. Data suggest also that cell accumulation of (59) Fe from TBI relies at least in part on an endocytosis-independent pathway. These data suggest that Zip8 and Steap2 play a major role in iron accumulation from NTBI and TBI by hippocampal neurons. Analysis of the expression and localization of known iron uptake transporters demonstrated that Zip8 makes a major contribution to iron accumulation in primary cultures of rat embryonic hippocampal neurons. These cells exhibit uptake pathways for ferrous and ferric iron (non-transferrin-bound iron, NTBI in figure) and for transferrin-bound iron; the ferrireductases Steap2 and SDR2 support the uptake of ferric iron substrates. Zip8 and Steap2 are strongly expressed in the plasma membrane of both soma and processes, implying a crucial role in iron accumulation from NTBI and transferrin-bound iron (TBI) by hippocampal neurons.
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Affiliation(s)
- Changyi Ji
- Department of Biochemistry, State University of New York, School of Medicine and Biomedical Sciences Buffalo, Buffalo, New York, USA
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25
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Iron transport across the blood-brain barrier: development, neurovascular regulation and cerebral amyloid angiopathy. Cell Mol Life Sci 2014; 72:709-27. [PMID: 25355056 DOI: 10.1007/s00018-014-1771-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/10/2014] [Accepted: 10/23/2014] [Indexed: 12/14/2022]
Abstract
There are two barriers for iron entry into the brain: (1) the brain-cerebrospinal fluid (CSF) barrier and (2) the blood-brain barrier (BBB). Here, we review the literature on developmental iron accumulation by the brain, focusing on the transport of iron through the brain microvascular endothelial cells (BMVEC) of the BBB. We review the iron trafficking proteins which may be involved in the iron flux across BMVEC and discuss the plausible mechanisms of BMVEC iron uptake and efflux. We suggest a model for how BMVEC iron uptake and efflux are regulated and a mechanism by which the majority of iron is trafficked across the developing BBB under the direct guidance of neighboring astrocytes. Thus, we place brain iron uptake in the context of the neurovascular unit of the adult brain. Last, we propose that BMVEC iron is involved in the aggregation of amyloid-β peptides leading to the progression of cerebral amyloid angiopathy which often occurs prior to dementia and the onset of Alzheimer's disease.
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Montalbetti N, Simonin A, Dalghi MG, Kovacs G, Hediger MA. Development and Validation of a Fast and Homogeneous Cell-Based Fluorescence Screening Assay for Divalent Metal Transporter 1 (DMT1/SLC11A2) Using the FLIPR Tetra. ACTA ACUST UNITED AC 2014; 19:900-8. [PMID: 24505080 DOI: 10.1177/1087057114521663] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/07/2014] [Indexed: 11/16/2022]
Abstract
Divalent metal ion transporter 1 (DMT1) is a proton-coupled Fe(2+)transporter that is essential for iron uptake in enterocytes and for transferrin-associated endosomal iron transport in many other cell types. DMT1 dysfunction is associated with several diseases such as iron overload disorders and neurodegenerative diseases. The main objective of the present work is to develop and validate a fluorescence-based screening assay for DMT1 modulators. We found that Fe(2+)or Cd(2+)influx could be reliably monitored in calcium 5-loaded DMT1-expressing HEK293 cells using the FLIPR Tetra fluorescence microplate reader. DMT1-mediated metal transport shows saturation kinetics depending on the extracellular substrate concentration, with a K0.5value of 1.4 µM and 3.5 µM for Fe(2+)and Cd(2+), respectively. In addition, Cd(2+)was used as a substrate for DMT1, and we find a Kivalue of 2.1 µM for a compound (2-(3-carbamimidoylsulfanylmethyl-benzyl)-isothiourea) belonging to the benzylisothioureas family, which has been identified as a DMT1 inhibitor. The optimized screening method using this compound as a reference demonstrated a Z' factor of 0.51. In summary, we developed and validated a sensitive and reproducible cell-based fluorescence assay suitable for the identification of compounds that specifically modulate DMT1 transport activity.
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Affiliation(s)
- Nicolas Montalbetti
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Switzerland
| | - Alexandre Simonin
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Switzerland
| | - Marianela G Dalghi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Switzerland
| | - Gergely Kovacs
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Switzerland
| | - Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Switzerland
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Wolff NA, Ghio AJ, Garrick LM, Garrick MD, Zhao L, Fenton RA, Thévenod F. Evidence for mitochondrial localization of divalent metal transporter 1 (DMT1). FASEB J 2014; 28:2134-45. [PMID: 24448823 DOI: 10.1096/fj.13-240564] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In mammalian cells, mitochondria receive most incoming iron, yet no entry pathway for iron at the outer mitochondrial membrane (OMM) has been characterized. Our results show that the divalent metal transporter 1 (DMT1) occurs in the OMM. Immunoblots detected DMT1 in mitochondria from a pneumocyte cell model in their OMM. Using the split-ubiquitin yeast 2-hybrid system, we found that cytochrome c oxidase subunit II (COXII) and the translocase of OMM 6-kDa subunit (Tom6) homologue interact with DMT1. COXII coimmunoprecipitates with DMT1. There are 4 DMT1 isoforms that differ at the N and C termini. Using HEK293 cells that inducibly express all of the 4 ends of DMT1, we found all of them in the OMM, as detected by immunoblots after cell fractionation, and in isolated mitochondria, as detected by immunofluorescence. Immunoblot analysis of purified cell fractions from rat renal cortex confirmed and extended these results to the kidney, which expressed high levels of DMT1. Immunogold labeling detected DMT1 colocalization in mitochondria with the voltage-dependent anion-selective channel protein-1, which is expressed in the OMM. We suggest that DMT1 not only exports iron from endosomes, but also serves to import the metal into the mitochondria.
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Affiliation(s)
- Natascha A Wolff
- 1Department of Physiology and Pathophysiology and ZBAF, University of Witten/Herdecke, Stockumer Strasse 12, D-58453 Witten, Germany. F.T.,
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28
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Arredondo M, Mendiburo MJ, Flores S, Singleton ST, Garrick MD. Mouse divalent metal transporter 1 is a copper transporter in HEK293 cells. Biometals 2013; 27:115-23. [PMID: 24327293 DOI: 10.1007/s10534-013-9691-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/01/2013] [Indexed: 01/14/2023]
Abstract
Divalent Metal Transporter 1 (DMT1) is an apical Fe transporter in the duodenum and is involved in endosomal Fe export. Four protein isoforms have been described for DMT1, two from mRNA with an iron responsive element (IRE) and two from mRNA without it. The sets of two begin in exon 1A or 2. We have characterized copper transport using mouse 2/-IRE DMT1 during regulated ectopic expression. HEK293 cells carrying a TetR:Hyg element were stably transfected with pDEST31 containing a 2/-IRE construct. (64)Cu(1+) incorporation in doxycycline treated cells exhibited 18.6 and 30.0-fold increases in Cu content, respectively when were exposed to 10 and 100 μM of extracellular Cu. Cu content was ~4-fold above that of parent cells or cells carrying just the vector. (64)Cu uptake in transfected cells pre-incubated with 5 μM of Cu-His revealed a Vmax and Km of 11.98 ± 0.52 pmol mg protein(-1) min(-1) and 2.03 ± 0.03 μM, respectively. Doxycycline-stimulated Cu uptake was linear with time. The rates of apical Cu uptake decreased and transepithelial transport increased when intracellular Cu increased. The optimal pH for Cu transport was 6.5; uptake of Cu was temperature dependent. Silver does not inhibit Cu uptake in cells carrying the vector. In conclusion, Cu uptake in HEK293 cells that over-expressed the 2/-IRE isoform of DMT1 transporter supports our earlier contention that DMT1 transports Cu as Cu(1+).
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Affiliation(s)
- Miguel Arredondo
- Micronutrients Laboratory, Nutrition Institute and Food Technology (INTA), Universidad de Chile, El Líbano 5524, Macul, Santiago, Chile,
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29
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Jiang L, Garrick MD, Garrick LM, Zhao L, Collins JF. Divalent metal transporter 1 (Dmt1) mediates copper transport in the duodenum of iron-deficient rats and when overexpressed in iron-deprived HEK-293 cells. J Nutr 2013; 143:1927-33. [PMID: 24089420 PMCID: PMC3827639 DOI: 10.3945/jn.113.181867] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Intracellular copper-binding proteins (metallothionein I/II) and a copper exporter (Menkes copper-transporting ATPase) are upregulated in duodenal enterocytes from iron-deficient rats, consistent with copper accumulation in the intestinal mucosa. How copper enters enterocytes during iron deficiency is, however, not clear. Divalent metal transporter 1 (Dmt1), the predominant iron importer in the mammalian duodenum, also transports other metal ions, possibly including copper. Given this possibility and that Dmt1 expression is upregulated by iron deprivation, we sought to test the hypothesis that Dmt1 transports copper during iron deficiency. Two model systems were utilized: the Belgrade (b) rat, expressing mutant Dmt1, and an inducible Dmt1-overexpression cell culture system. Mutant rats (b/b) were fed a semipurified, AIN93G-based control diet and phenotypically normal littermates (+/b) were fed control or iron-deficient diets for ~14 wk. An everted gut sleeve technique and a colorimetric copper quantification assay were utilized to assess duodenal copper transport. The control diet-fed +/b rats had normal hematological parameters, whereas iron-deprived +/b and b/b rats were iron deficient and Dmt1 mRNA and protein levels increased. Importantly, duodenal copper transport was similar in the control +/b and b/b rats; however, it significantly increased (~4-fold) in the iron-deprived +/b rats. Additional experiments in Dmt1 overexpressing HEK-293 cells showed that copper ((64)Cu) uptake was stimulated (∼3-fold) in the presence of an iron chelator. Dmt1 transcript stabilization due to a 3' iron-responsive element was also documented, likely contributing to increased transport activity. In summary, these studies suggest that Dmt1 enhances copper uptake into duodenal enterocytes during iron deprivation.
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Affiliation(s)
- Lingli Jiang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL; and
| | | | | | - Lin Zhao
- Department of Biochemistry, University at Buffalo, Buffalo, NY
| | - James F. Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL; and,To whom correspondence should be addressed. E-mail:
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30
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The N-terminal basolateral targeting signal unlikely acts alone in the differential trafficking of membrane transporters in MDCK cells. Biochemistry 2013; 52:5103-5116. [PMID: 23837633 DOI: 10.1021/bi4005914] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have shown previously, using confocal imaging and transport assays, that the N-terminus of sodium-dependent vitamin C transporter 2 (SVCT2) can redirect apical SVCT1 to the basolateral membrane. Here, the SVCT model was used to further characterize the basolateral targeting peptide signal. Both the length (31 amino acids) and sequence accuracy of the N-terminus of SVCT2 were found to be important in basolateral targeting activity, suggesting a structural requirement. However, the N-terminal basolateral targeting sequence did not appear to act alone, based on analyses of heterologous chimeras. Although diverse N-terminal basolateral targeting signals from multipass membrane proteins can all redirect apical protein from the same gene family to the basolateral membrane, none of the N-terminal basolateral targeting signals can redirect the transmembrane and C-terminal regions from a different gene family. Instead, the presence of these heterologous N-terminal basolateral targeting signals affected the trafficking of otherwise apical protein, causing their accumulation in a stable tubulin-like non-actin structure. Nontargeting N-terminal sequences had no effect. Similar protein retention was observed previously and in this study when the C-terminus of apical or basolateral protein was mutated. These results suggest that the N- and C-termini interact, directly or indirectly, within each gene family for basolateral targeting. Circular dichroism and two-dimensional nuclear magnetic resonance analyses both found a lack of regular secondary structure in the conserved N-terminus of SVCT2, consistent with the presence of partner(s) in the targeting unit. Our finding, a departure from the prevailing single-peptide motif model, is consistent with the evolution of basolateral transporters from the corresponding apical genes. The interaction among the N-terminus, its partner(s), and the cellular basolateral targeting machinery needs to be further elucidated.
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Gruppi F, Liang J, Bartelle BB, Royzen M, Turnbull DH, Canary JW. Supramolecular metal displacement allows on-fluorescence analysis of manganese(II) in living cells. Chem Commun (Camb) 2012; 48:10778-80. [PMID: 23023093 PMCID: PMC3722360 DOI: 10.1039/c2cc34742c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Due to the importance of Mn(2+) ions in biological processes, it is of growing interest to develop protocols for analysis of Mn(2+) uptake and distribution in cells. A supramolecular metal displacement assay can provide ratiometric fluorescence detection of Mn(2+), allowing for quantitative and longitudinal analysis of Mn(2+) uptake in living cells.
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Affiliation(s)
- Francesca Gruppi
- Department of Chemistry, New York University, New York, NY 10003. Fax: 212-995-4367; Tel: 212-998-8422
| | - Jian Liang
- Department of Chemistry, New York University, New York, NY 10003. Fax: 212-995-4367; Tel: 212-998-8422
| | - Benjamin B. Bartelle
- Kimmel Center for Biology & Medicine at the Skirball Institute of Biomolecular Medicine, and Department of Radiology, New York University School of Medicine, New York, NY 10016
| | - Maksim Royzen
- Department of Chemistry, New York University, New York, NY 10003. Fax: 212-995-4367; Tel: 212-998-8422
| | - Daniel H. Turnbull
- Kimmel Center for Biology & Medicine at the Skirball Institute of Biomolecular Medicine, and Department of Radiology, New York University School of Medicine, New York, NY 10016
| | - James W. Canary
- Department of Chemistry, New York University, New York, NY 10003. Fax: 212-995-4367; Tel: 212-998-8422
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Bartelle BB, Szulc KU, Suero-Abreu GA, Rodriguez JJ, Turnbull DH. Divalent metal transporter, DMT1: a novel MRI reporter protein. Magn Reson Med 2012; 70:842-50. [PMID: 23065715 DOI: 10.1002/mrm.24509] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/02/2012] [Accepted: 08/31/2012] [Indexed: 12/22/2022]
Abstract
Manganese (Mn)-enhanced MRI (MEMRI) has found a growing number of applications in anatomical and functional imaging in small animals, based on the cellular uptake of Mn ions in the brain, heart, and other organs. Previous studies have relied on endogenous mechanisms of paramagnetic Mn ion uptake and enhancement. To genetically control MEMRI signals, we reverse engineered a major component of the molecular machinery involved in Mn uptake, the divalent metal transporter, DMT1. DMT1 provides positive cellular enhancement in a manner that is highly sensitive and dynamic, allowing greater spatial and temporal resolution for MRI compared to previously proposed MRI reporters such as ferritin. We characterized the MEMRI signal enhancement properties of DMT1-expressing cells, both in vitro and in vivo in mouse models of cancer and brain development. Our results show that DMT1 provides an effective genetic MRI reporter for a wide range of biological and preclinical imaging applications.
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Affiliation(s)
- Benjamin B Bartelle
- Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA; Molecular Biophysics Graduate Program, New York University School of Medicine, New York, New York, USA
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33
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Lopin KV, Gray IP, Obejero-Paz CA, Thévenod F, Jones SW. Fe²⁺ block and permeation of CaV3.1 (α1G) T-type calcium channels: candidate mechanism for non-transferrin-mediated Fe²⁺ influx. Mol Pharmacol 2012; 82:1194-204. [PMID: 22973060 DOI: 10.1124/mol.112.080184] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Iron is a biologically essential metal, but excess iron can cause damage to the cardiovascular and nervous systems. We examined the effects of extracellular Fe²⁺ on permeation and gating of Ca(V)3.1 channels stably transfected in HEK293 cells, by using whole-cell recording. Precautions were taken to maintain iron in the Fe²⁺ state (e.g., use of extracellular ascorbate). With the use of instantaneous I-V currents (measured after strong depolarization) to isolate the effects on permeation, extracellular Fe²⁺ rapidly blocked currents with 2 mM extracellular Ca²⁺ in a voltage-dependent manner, as described by a Woodhull model with K(D) = 2.5 mM at 0 mV and apparent electrical distance δ = 0.17. Extracellular Fe²⁺ also shifted activation to more-depolarized voltages (by ∼10 mV with 1.8 mM extracellular Fe²⁺) somewhat more strongly than did extracellular Ca²⁺ or Mg²⁺, which is consistent with a Gouy-Chapman-Stern model with surface charge density σ = 1 e(-)/98 Ų and K(Fe) = 4.5 M⁻¹ for extracellular Fe²⁺. In the absence of extracellular Ca²⁺ (and with extracellular Na⁺ replaced by TEA), Fe²⁺ carried detectable, whole-cell, inward currents at millimolar concentrations (73 ± 7 pA at -60 mV with 10 mM extracellular Fe²⁺). With a two-site/three-barrier Eyring model for permeation of Ca(V)3.1 channels, we estimated a transport rate for Fe²⁺ of ∼20 ions/s for each open channel at -60 mV and pH 7.2, with 1 μM extracellular Fe²⁺ (with 2 mM extracellular Ca²⁺). Because Ca(V)3.1 channels exhibit a significant "window current" at that voltage (open probability, ∼1%), Ca(V)3.1 channels represent a likely pathway for Fe²⁺ entry into cells with clinically relevant concentrations of extracellular Fe²⁺.
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Affiliation(s)
- Kyle V Lopin
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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Illing AC, Shawki A, Cunningham CL, Mackenzie B. Substrate profile and metal-ion selectivity of human divalent metal-ion transporter-1. J Biol Chem 2012; 287:30485-96. [PMID: 22736759 PMCID: PMC3436370 DOI: 10.1074/jbc.m112.364208] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 06/18/2012] [Indexed: 12/13/2022] Open
Abstract
Divalent metal-ion transporter-1 (DMT1) is a H(+)-coupled metal-ion transporter that plays essential roles in iron homeostasis. DMT1 exhibits reactivity (based on evoked currents) with a broad range of metal ions; however, direct measurement of transport is lacking for many of its potential substrates. We performed a comprehensive substrate-profile analysis for human DMT1 expressed in RNA-injected Xenopus oocytes by using radiotracer assays and the continuous measurement of transport by fluorescence with the metal-sensitive PhenGreen SK fluorophore. We provide validation for the use of PhenGreen SK fluorescence quenching as a reporter of cellular metal-ion uptake. We determined metal-ion selectivity under fixed conditions using the voltage clamp. Radiotracer and continuous measurement of transport by fluorescence assays revealed that DMT1 mediates the transport of several metal ions that were ranked in selectivity by using the ratio I(max)/K(0.5) (determined from evoked currents at -70 mV): Cd(2+) > Fe(2+) > Co(2+), Mn(2+) ≫ Zn(2+), Ni(2+), VO(2+). DMT1 expression did not stimulate the transport of Cr(2+), Cr(3+), Cu(+), Cu(2+), Fe(3+), Ga(3+), Hg(2+), or VO(+). (55)Fe(2+) transport was competitively inhibited by Co(2+) and Mn(2+). Zn(2+) only weakly inhibited (55)Fe(2+) transport. Our data reveal that DMT1 selects Fe(2+) over its other physiological substrates and provides a basis for predicting the contribution of DMT1 to intestinal, nasal, and pulmonary absorption of metal ions and their cellular uptake in other tissues. Whereas DMT1 is a likely route of entry for the toxic heavy metal cadmium, and may serve the metabolism of cobalt, manganese, and vanadium, we predict that DMT1 should contribute little if at all to the absorption or uptake of zinc. The conclusion in previous reports that copper is a substrate of DMT1 is not supported.
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Affiliation(s)
| | - Ali Shawki
- From the Department of Molecular and Cellular Physiology and
- the Systems Biology and Physiology Program, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | | | - Bryan Mackenzie
- From the Department of Molecular and Cellular Physiology and
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1B/(-)IRE DMT1 expression during brain ischemia contributes to cell death mediated by NF-κB/RelA acetylation at Lys310. PLoS One 2012; 7:e38019. [PMID: 22666436 PMCID: PMC3362534 DOI: 10.1371/journal.pone.0038019] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 04/30/2012] [Indexed: 01/31/2023] Open
Abstract
The molecular mechanisms responsible for increasing iron and neurodegeneration in brain ischemia are an interesting area of research which could open new therapeutic approaches. Previous evidence has shown that activation of nuclear factor kappa B (NF-κB) through RelA acetylation on Lys310 is the prerequisite for p50/RelA-mediated apoptosis in cellular and animal models of brain ischemia. We hypothesized that the increase of iron through a NF-κB-regulated 1B isoform of the divalent metal transporter-1 (1B/DMT1) might contribute to post-ischemic neuronal damage. Both in mice subjected to transient middle cerebral artery occlusion (MCAO) and in neuronally differentiated SK-N-SH cells exposed to oxygen-glucose-deprivation (OGD), 1A/DMT1 was only barely expressed while the 1B/DMT1 without iron-response-element (−IRE) protein and mRNA were early up-regulated. Either OGD or over-expression of 1B/(−)IRE DMT1 isoform significantly increased iron uptake, as detected by total reflection X-ray fluorescence, and iron-dependent cell death. Iron chelation by deferoxamine treatment or (−)IRE DMT1 RNA silencing displayed significant neuroprotection against OGD which concomitantly decreased intracellular iron levels. We found evidence that 1B/(−)IRE DMT1 was a target gene for RelA activation and acetylation on Lys310 residue during ischemia. Chromatin immunoprecipitation analysis of the 1B/DMT1 promoter showed there was increased interaction with RelA and acetylation of H3 histone during OGD exposure of cortical neurons. Over-expression of wild-type RelA increased 1B/DMT1 promoter-luciferase activity, the (−)IRE DMT1 protein, as well as neuronal death. Expression of the acetylation-resistant RelA-K310R construct, which carried a mutation from lysine 310 to arginine, but not the acetyl-mimic mutant RelA-K310Q, down-regulated the 1B/DMT1 promoter, consequently offering neuroprotection. Our data showed that 1B/(−)IRE DMT1 expression and intracellular iron influx are early downstream responses to NF-κB/RelA activation and acetylation during brain ischemia and contribute to the pathogenesis of stroke-induced neuronal damage.
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36
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Lee BK, Kim Y. Effects of menopause on blood manganese levels in women: analysis of 2008-2009 Korean National Health and Nutrition Examination Survey data. Neurotoxicology 2012; 33:401-5. [PMID: 22542452 DOI: 10.1016/j.neuro.2012.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Revised: 04/12/2012] [Accepted: 04/12/2012] [Indexed: 12/18/2022]
Abstract
INTRODUCTION We present data from the Korean National Health and Nutrition Examination Survey 2008-2009 on the association between blood manganese (Mn) levels and menopausal status in women. METHODS The present analysis was restricted to female participants who completed the health examination survey, including blood Mn measurements (n=1826). Menopausal status was categorized into pre- and post-menopausal. Multivariable linear regression analyses were performed to determine whether menopausal status or serum ferritin were significant predictors of blood Mn level and to investigate whether menopausal status modifies the association between blood Mn and serum ferritin after adjusting for covariates. RESULTS The geometric means (GMs) of blood Mn in the low and low-normal serum ferritin groups were significantly higher than the GM of blood Mn in the normal group. The GM of blood Mn in premenopausal women was significantly higher than in postmenopausal women Multivariable linear regression analyses showed that both serum ferritin and menopausal status were predictors of blood Mn, after adjusting for various covariates, and menopausal status acted as a modifier of the effect of ferritin on blood Mn levels. Blood Mn levels were 11.0% and 22.7% lower in premenopausal women when serum ferritin increased from 10 μg/dL to 60 and 100 μg/dL, respectively, but the decrease in blood Mn based on the increase in serum ferritin was minimal in postmenopausal women. DISCUSSION To our knowledge, this is the first report that menopausal status was a predictor of blood Mn level after adjusting for serum ferritin. In conclusion, the present study showed that both serum ferritin and menopausal status were predictors of blood Mn, after adjusting for various covariates, and menopausal status acted as a modifier of the effect of ferritin on blood Mn levels.
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Affiliation(s)
- Byung-Kook Lee
- Institute of Environmental & Occupational Medicine, Soonchunhyang University 646 Eupnae-ri, Shinchang-myun, Asan-si, Choongnam 336-745 South Korea
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Mechanistic analysis of iron accumulation by endothelial cells of the BBB. Biometals 2012; 25:665-75. [PMID: 22434419 DOI: 10.1007/s10534-012-9538-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 03/04/2012] [Indexed: 01/06/2023]
Abstract
The mechanism(s) by which iron in blood is transported across the blood-brain barrier (BBB) remains controversial. Here we have examined the first step of this trans-cellular pathway, namely the mechanism(s) of iron uptake into human brain microvascular endothelial cells (hBMVEC). We show that hBMVEC actively reduce non-transferrin bound Fe(III) (NTBI) and transferrin-bound Fe(III) (TBI); this activity is associated with one or more ferrireductases. Efficient, exo-cytoplasmic ferri-reduction from TBI is dependent upon transferrin receptor (TfR), also. Blocking holo-Tf binding with an anti-TfR antibody significantly decreases the reduction of iron from transferrin by hBMVEC, suggesting that holo-Tf needs to bind to TfR in order for efficient reduction to occur. Ferri-reduction from TBI significantly decreases when hBMVEC are pre-treated with Pt(II), an inhibitor of cell surface reductase activity. Uptake of (59)Fe from (59)Fe-Tf by endothelial cells is inhibited by 50 % when ferrozine is added to solution; in contrast, no inhibition occurs when cells are alkalinized with NH(4)Cl. This indicates that the iron reduced from holo-transferrin at the plasma membrane accounts for at least 50 % of the iron uptake observed. hBMVEC-dependent reduction and uptake of NTBI utilizes a Pt(II)-insensitive reductase. Reductase-independent uptake of Fe(II) by hBMVEC is inhibited up to 50 % by Zn(II) and/or Mn(II) by a saturable process suggesting that redundant Fe(II) transporters exist in the hBMVEC plasma membrane. These results are the first to demonstrate multiple mechanism(s) of TBI and NTBI reduction and uptake by endothelial cells (EC) of the BBB.
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Garrick MD, Zhao L, Roth JA, Jiang H, Feng J, Foot NJ, Dalton H, Kumar S, Garrick LM. Isoform specific regulation of divalent metal (ion) transporter (DMT1) by proteasomal degradation. Biometals 2012; 25:787-93. [PMID: 22310887 DOI: 10.1007/s10534-012-9522-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 01/09/2012] [Indexed: 11/24/2022]
Abstract
Divalent metal ion transporter (DMT1) is the major transporter for iron entrance into mammalian cells and iron exit from endosomes during the transferrin cycle. Four major mRNA isoforms correspond to four protein isoforms, differing at 5'/3' and N-/C-termini, respectively. Isoforms are designated 1A versus 1B reflecting where transcription starts or +iron responsive element (+IRE) versus -IRE reflecting the presence/absence of an IRE in the 3' end of the mRNA. These differences imply regulation at transcriptional and posttranscriptional levels. Many proteins are degraded by a ubiquitination-dependent mechanism. Two different ubiquitin ligases (E3s) appear to be involved in DMT1 ubiquitination: Parkin or neuronal precursor cell-expressed developmentally downregulated 4 (Nedd4) family E3s which often utilize Nedd4 family interacting protein-1 and -2 (Ndfip1 and 2) to ubiquitinate their substrate proteins. Prior data suggest that Parkin ubiquitinates 1B DMT1 but not 1A DMT1 while Nedd4/Ndfips ligate ubiquitin to DMT1 in the duodenum where 1A/+IRE DMT1 predominates. Our assay for whether these systems target DMT1 depends on two HEK293 cell lines that express permanently transfected 1A/+IRE DMT1 or 1B/-IRE DMT1 after induction by doxycycline. Transient transfection with a Parkin construct before induction diminishes 1B/-IRE DMT1 detected by immune-blots but not 1A/+IRE DMT1. Mutant Parkin serves as a control that does not affect DMT1 levels. Thus DMT1 regulation in an isoform specific fashion can occur by ubiquitination and the events involved have implications for DMT1 function and disease processes.
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Affiliation(s)
- Michael D Garrick
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA.
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Shawki A, Knight PB, Maliken BD, Niespodzany EJ, Mackenzie B. H(+)-coupled divalent metal-ion transporter-1: functional properties, physiological roles and therapeutics. CURRENT TOPICS IN MEMBRANES 2012. [PMID: 23177986 DOI: 10.1016/b978-0-12-394316-3.00005-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Divalent metal-ion transporter-1 (DMT1) is a widely expressed, iron-preferring membrane transport protein. Animal models establish that DMT1 plays indispensable roles in intestinal nonheme-iron absorption and iron acquisition by erythroid precursor cells. Rare mutations in human DMT1 result in severe microcytic-hypochromic anemia. When we express DMT1 in RNA-injected Xenopus oocytes, we observe rheogenic Fe(2+) transport that is driven by the proton electrochemical potential gradient. In that same preparation, DMT1 also transports cadmium and manganese but not copper. Whether manganese metabolism relies upon DMT1 remains unclear but DMT1 contributes to the effects of overexposure to cadmium and manganese in some tissues. There exist at least four DMT1 isoforms that arise from variant transcription of the SLC11A2 gene. Whereas these isoforms display identical functional properties, N- and C-terminal variations contain cues that direct the cell-specific targeting of DMT1 isoforms to discrete subcellular compartments (plasma membrane, endosomes, and lysosomes). An iron-responsive element (IRE) in the mRNA 3'-untranslated region permits the regulation of some isoforms by iron status, and additional mechanisms by which DMT1 is regulated are emerging. Natural-resistance-associated macrophage protein-1 (NRAMP1)-the only other member of the mammalian SLC11 gene family-contributes to antimicrobial function by extruding from the phagolysosome divalent metal ions (e.g. Mn(2+)) that may be essential cofactors for bacteria-derived enzymes or required for bacterial growth. The principal or only intestinal nonheme-iron transporter, DMT1 is a validated therapeutic target in hereditary hemochromatosis (HHC) and other iron-overload disorders.
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Affiliation(s)
- Ali Shawki
- Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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Iron transport machinery of human cells: players and their interactions. CURRENT TOPICS IN MEMBRANES 2012; 69:67-93. [PMID: 23046647 DOI: 10.1016/b978-0-12-394390-3.00003-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Organisms, like cells, maintain tight control of iron. In humans as well as other mammals, control is achieved through the regulation of iron uptake into the body rather than through the excretion of iron. The mechanisms by which humans and mice regulate both iron uptake and the distribution of iron within the body and cells are reviewed. Special emphasis is given to the iron transporters involved in this process.
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Madejczyk MS, Ballatori N. The iron transporter ferroportin can also function as a manganese exporter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:651-7. [PMID: 22178646 DOI: 10.1016/j.bbamem.2011.12.002] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 11/28/2011] [Accepted: 12/02/2011] [Indexed: 01/13/2023]
Abstract
The present study examined the hypothesis that the iron exporter ferroportin (FPN1/SLC40A1) can also mediate cellular export of the essential trace element manganese, using Xenopus laevis oocytes expressing human FPN1. When compared to oocytes expressing only the divalent metal transporter-1 (DMT1/NRAMP2), (54)Mn accumulation was lower in oocytes also expressing FPN1. FPN1-expressing oocytes exported more (54)Mn than control oocytes (26.6±0.6% versus 7.1±0.5%, respectively, over 4h at pH 7.4 when preloaded with approximately 16μM (54)Mn); however, there was no difference in (54)Mn uptake between control and FPN1-expressing oocytes. FPN1-mediated Mn export was concentration dependent and could be partially cis-inhibited by 100μM Fe, Co, and Ni, but not by Rb. In addition, Mn export ability was significantly reduced when the extracellular pH was reduced from 7.4 to 5.5, and when Na(+) was substituted with K(+) in the incubation media. These results indicate that Mn is a substrate for FPN1, and that this export process is inhibited by a low extracellular pH and by incubation in a high K(+) medium, indicating the involvement of transmembrane ion gradients in FPN1-mediated transport.
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Affiliation(s)
- Michael S Madejczyk
- Department of Environmental Medicine, University of Rochester School of Medicine, Rochester, NY, USA.
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Martin DP, Anantharam V, Jin H, Witte T, Houk R, Kanthasamy A, Kanthasamy AG. Infectious prion protein alters manganese transport and neurotoxicity in a cell culture model of prion disease. Neurotoxicology 2011; 32:554-62. [PMID: 21871919 DOI: 10.1016/j.neuro.2011.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 07/20/2011] [Accepted: 07/21/2011] [Indexed: 01/26/2023]
Abstract
Protein misfolding and aggregation are considered key features of many neurodegenerative diseases, but biochemical mechanisms underlying protein misfolding and the propagation of protein aggregates are not well understood. Prion disease is a classical neurodegenerative disorder resulting from the misfolding of endogenously expressed normal cellular prion protein (PrP(C)). Although the exact function of PrP(C) has not been fully elucidated, studies have suggested that it can function as a metal binding protein. Interestingly, increased brain manganese (Mn) levels have been reported in various prion diseases indicating divalent metals also may play a role in the disease process. Recently, we reported that PrP(C) protects against Mn-induced cytotoxicity in a neural cell culture model. To further understand the role of Mn in prion diseases, we examined Mn neurotoxicity in an infectious cell culture model of prion disease. Our results show CAD5 scrapie-infected cells were more resistant to Mn neurotoxicity as compared to uninfected cells (EC(50)=428.8 μM for CAD5 infected cells vs. 211.6 μM for uninfected cells). Additionally, treatment with 300 μM Mn in persistently infected CAD5 cells showed a reduction in mitochondrial impairment, caspase-3 activation, and DNA fragmentation when compared to uninfected cells. Scrapie-infected cells also showed significantly reduced Mn uptake as measured by inductively coupled plasma-mass spectrometry (ICP-MS), and altered expression of metal transporting proteins DMT1 and transferrin. Together, our data indicate that conversion of PrP to the pathogenic isoform enhances its ability to regulate Mn homeostasis, and suggest that understanding the interaction of metals with disease-specific proteins may provide further insight to protein aggregation in neurodegenerative diseases.
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Affiliation(s)
- Dustin P Martin
- Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicity, Ames, IA 50011, USA
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Kawanai T, Fujinaga M, Koizumi K, Kurotani I, Hashimoto E, Satoh M, Imai S, Miyoshi N, Oyama Y. Some characteristics of membrane Cd2+ transport in rat thymocytes: an analysis using Fluo-3. Biometals 2011; 24:903-14. [DOI: 10.1007/s10534-011-9444-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 03/17/2011] [Indexed: 01/13/2023]
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Garrick MD. Human iron transporters. GENES AND NUTRITION 2010; 6:45-54. [PMID: 21437029 DOI: 10.1007/s12263-010-0184-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 08/24/2010] [Indexed: 01/17/2023]
Abstract
Human iron transporters manage iron carefully because tissues need iron for critical functions, but too much iron increases the risk of reactive oxygen species. Iron acquisition occurs in the duodenum via divalent metal transporter (DMT1) and ferroportin. Iron trafficking depends largely on the transferrin cycle. Nevertheless, non-digestive tissues have a variety of other iron transporters that may render DMT1 modestly redundant, and DMT1 levels exceed those needed for the just-mentioned tasks. This review begins to consider why and also describes advances after 2008 that begin to address this challenge.
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Affiliation(s)
- Michael D Garrick
- Department of Biochemistry, 140 Farber Hall, SUNY at Buffalo, 3435 Main St., Buffalo, NY 14214 USA
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Meltzer HM, Brantsaeter AL, Borch-Iohnsen B, Ellingsen DG, Alexander J, Thomassen Y, Stigum H, Ydersbond TA. Low iron stores are related to higher blood concentrations of manganese, cobalt and cadmium in non-smoking, Norwegian women in the HUNT 2 study. ENVIRONMENTAL RESEARCH 2010; 110:497-504. [PMID: 20381026 DOI: 10.1016/j.envres.2010.03.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 02/09/2010] [Accepted: 03/17/2010] [Indexed: 05/20/2023]
Abstract
Low iron (Fe) stores may influence absorption or transport of divalent metals in blood. To obtain more knowledge about such associations, the divalent metal ions cadmium (Cd), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn) and lead (Pb) and parameters of Fe metabolism (serum ferritin, haemoglobin (Hb) and transferrin) were investigated in 448 healthy, menstruating non-smoking women, age 20-55 years (mean 38 years), participating in the Norwegian HUNT 2 study. The study population was stratified for serum ferritin: 257 were iron-depleted (serum ferritin < 12 microg/L) and 84 had iron deficiency anaemia (serum ferritin < 12 microg/L and Hb < 120 g/L). The low ferritin group had increased blood concentrations of Mn, Co and Cd but normal concentrations of Cu, Zn and Pb. In multiple regression models, ferritin emerged as the main determinant of Mn, Co and Cd (p < 0.001), while no significant associations with Cu, Zn and Pb were found. Adjusted r(2) for the models were 0.28, 0.48 and 0.34, respectively. Strong positive associations between blood concentrations of Mn, Co and Cd were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the six divalent metals studied. Very mild anaemia (110 < or = Hb < 120 g/L) did not seem to have any effect independent of low ferritin. Approximately 26% of the women with iron deficiency anaemia had high concentrations of all of Mn, Co and Cd as opposed to 2.3% of iron-replete subjects. The results confirm that low serum ferritin may have an impact on body kinetics of certain divalent metal ions, but not all. Only a fraction of women with low iron status exhibited an increased blood concentration of divalent metals, providing indication of complexities in the body's handling of these metals.
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Affiliation(s)
- Helle Margrete Meltzer
- Division of Environmental Medicine, Department of Food Safety and Nutrition, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo, Norway.
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Transferrin-iron routing to the cytosol and mitochondria as studied by live and real-time fluorescence. Biochem J 2010; 429:185-93. [PMID: 20408812 DOI: 10.1042/bj20100213] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study we analysed the mechanism of intracellular routing of iron acquired by erythroid cells via receptor-mediated endocytosis of Tf-Fe [Tf (transferrin)-iron]. Using real-time fluorimetry and flow cytometry, in conjunction with targeted fluorescent metal sensors, we monitored concurrently the cytosolic and mitochondrial changes in labile iron evoked by endocytosed Tf-Fe. In K562 human erythroleukaemia cells, most of the Tf-Fe was found to be delivered to the cytosolic labile iron pool by a saturable mechanism [60-120 nM Km (app)] that was quantitatively dependent on: Tf receptor levels, endosomal acidification/reduction for dislodging iron from Tf and ensuing translocation of labile iron into the cytosolic compartment. The parallel ingress of iron to mitochondria was also saturable, but with a relatively lower Km (app) (26-42 nM) and a lower maximal ingress per cell than into the cytosol. The ingress of iron into the mitochondrial labile iron pool was blocked by cytosol-targeted iron chelators, implying that a substantial fraction of Tf-Fe delivered to these organelles passes through the cytosol in non-occluded forms that remain accessible to high-affinity ligands. The present paper is the first report describing intracellular iron routing measured in intact cells in real-time and in quantitative terms, opening the road for also exploring the process in mixed-cell populations of erythroid origin.
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Calcium-channel blockers do not affect iron transport mediated by divalent metal-ion transporter-1. Blood 2010; 115:4148-9. [PMID: 20489062 DOI: 10.1182/blood-2010-03-274738] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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Keenan BM, Robinson SR, Bishop GM. Effects of carboxylic acids on the uptake of non-transferrin-bound iron by astrocytes. Neurochem Int 2010; 56:843-9. [DOI: 10.1016/j.neuint.2010.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 03/01/2010] [Accepted: 03/15/2010] [Indexed: 11/30/2022]
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Andolfo I, De Falco L, Asci R, Russo R, Colucci S, Gorrese M, Zollo M, Iolascon A. Regulation of divalent metal transporter 1 (DMT1) non-IRE isoform by the microRNA Let-7d in erythroid cells. Haematologica 2010; 95:1244-52. [PMID: 20410187 DOI: 10.3324/haematol.2009.020685] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Divalent metal transporter 1 (DMT1) is a widely expressed metal-iron transporter gene encoding four variant mRNA transcripts, differing for alternative promoter at 5' (DMT1 1A and 1B) and alternative splicing at 3' UTR, differing by a specific sequence either containing or lacking an iron regulatory element (+IRE and -IRE, respectively). DMT1-IRE might be the major DMT1 isoform expressed in erythroid cells, although its regulation pathways are still unknown. DESIGN AND METHODS The microRNA (miRNA) Let-7d (miR-Let-7d) was selected by the analysis of four miRNAs, predicted to target the DMT1-IRE gene in CD34(+) hematopoietic progenitor cells, in K562 and in HEL cells induced to erythroid differentiation. Using a luciferase reporter assay we demonstrated the inhibition of DMT1-IRE by miR-Let-7d in K562 and HEL cells. The function of miR-Let-7d in erythroid cells was evaluated by the flow cytometry analysis of erythroid differentiation markers, by benzidine staining and by iron flame atomic absorption for the evaluation of iron concentration in the endosomes from K562 cells over-expressing miR-Let-7d. RESULTS We show that in erythroid cells, DMT1-IRE expression is under the regulation of miR-Let-7d. DMT1-IRE and miR-Let-7d are inversely correlated with CD34(+) cells, K562 and HEL cells during erythroid differentiation. Moreover, overexpression of miR-Let-7d decreases the expression of DMT1-IRE at the mRNA and protein levels in K562 and HEL cells. MiR-Let-7d impairs erythroid differentiation of K562 cells by accumulation of iron in the endosomes. CONCLUSIONS Overall, these data suggest that miR-Let-7d participates in the finely tuned regulation of iron metabolism by targeting DMT1-IRE isoform in erythroid cells.
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Affiliation(s)
- Immacolata Andolfo
- CEINGE, Biotecnologie Avanzate, Via, Comunale Margherita 482, 80145 Naples, Italy
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Tulpule K, Robinson SR, Bishop GM, Dringen R. Uptake of ferrous iron by cultured rat astrocytes. J Neurosci Res 2010; 88:563-71. [PMID: 19746426 DOI: 10.1002/jnr.22217] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Astrocytes are considered to play an important role in iron homeostasis of the brain, yet the mechanisms involved in the uptake of iron into astrocytes remain elusive. To investigate the uptake of iron into astrocytes, we have applied ferric ammonium citrate (FAC) to rat astrocyte-rich primary cultures. These cultures express the mRNAs of two membrane-bound ferric reductases, Dcytb and SDR2, and reduce extracellular ferric iron (100 muM) with a rate of 3.2 +/- 0.4 nmol/(hr x mg). This reduction rate is substantially lower than the rate of cellular iron accumulation from 100 muM FAC [24.7 +/- 8.9 nmol/(hr x mg)], which suggests that iron accumulation from FAC does at best partially depend on extracellular ferric reduction. Nonetheless, when the iron in FAC was almost completely reduced by an excess of exogenous ascorbate, astrocytes accumulated iron in a time- and concentration-dependent manner with specific iron accumulation rates that increased linearly for concentrations of up to 100 muM ferrous iron. This accumulation was attenuated by lowering the incubation temperature, by the presence of ferrous iron chelators, or by lowering the pH from 7.4 to 6.8. These data indicate that, in addition to the DMT1-mediated uptake of ferrous iron, astrocytes can accumulate ferric and ferrous iron by mechanisms that are independent of DMT1 or transferrin.
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Affiliation(s)
- Ketki Tulpule
- Center for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
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